This is a working overview of Tetrapeptide, written for readers who want more than a one-paragraph summary but less than a textbook.
Reviewed 2026-07-18. Anything still debated is marked as such rather than presented as settled.
Chemically, the molecule consists of four amino acid residues joined by three peptide bonds, with a free N-terminal amino group and a free C-terminal carboxyl group. Its molecular formula is C14H22N4O9, and its monoisotopic mass is approximately 390 daltons. The acidic glutamate and aspartate side chains give the peptide a net negative charge near neutral pH, a property that shapes its chromatographic behaviour and solubility profile. No disulfide bridges or other post-translational modifications are present, so the primary sequence alone defines the structure.
Most experimental work has been carried out in cell culture and animal models. Several reports describe changes in telomerase activity and proliferation in cultured cells, while rodent studies have examined lifespan, melatonin rhythm and reproductive endpoints. Human data remain limited, and much of the published clinical material consists of small trials with incomplete reporting of methods and controls. Whether the cell and animal findings translate into measurable effects in people is an open question, and the mechanistic basis of the reported telomerase changes is not fully established.
Discussions in the literature often conflate three distinct entities: the pineal extract epithalamin, the isolated tetrapeptide AEDG, and commercial preparations sold under similar names. Reviews citing older Russian-language studies sometimes omit detail on purity, route of administration and control groups, which makes cross-study comparison difficult. Researchers working with the compound generally note the need for independent replication, standardized enzyme assays, and clearer reporting of peptide identity. These caveats are relevant when weighing claims that appear in secondary sources rather than in primary reports.
Epitalon is a synthetic linear tetrapeptide with the sequence alanine–glutamate–aspartate–glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and the calculated mass is approximately 390.35 g/mol. The compound is made by solid-phase peptide synthesis rather than extracted from tissue, although early work described it as a short fragment of a peptide fraction obtained from bovine pineal extract. In the research literature the spelling epitalon and the variant epithalone both appear, while AEDG is the standard code used in peptide nomenclature.
Several names circulate for the same molecule, including epitalon, epithalone, epithalamin tetrapeptide, and the sequence code AEDG. A CAS registry number, 307297-39-8, is commonly cited for it, though catalogue entries should be checked against supplier documentation because mislabelled records occur. In its usual form the peptide carries free amino and carboxyl termini and is neither glycosylated nor lipidated. Researchers distinguish the defined tetrapeptide from epithalamin itself, a crude pineal preparation containing many peptides that is not chemically characterised.
| Property | Value | Notes |
|---|---|---|
| Chemical class | Linear tetrapeptide | Four residues joined by three peptide bonds |
| Sequence | Ala-Glu-Asp-Gly | Commonly abbreviated AEDG |
| Molecular formula | C14H22N4O9 | Free acid form |
| Monoisotopic mass | Approximately 390 Da | Matches values reported from mass spectrometry |
| Net charge near neutral pH | Negative | Contributed by glutamate and aspartate side chains |
Epitalon is the common name for a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, usually abbreviated AEDG. All four residues are proteinogenic amino acids, and the free peptide has a calculated mass near 390 grams per mole. Because the chain is short and carries no modifications, it is assembled readily by solid-phase synthesis and is distributed mainly as a freeze-dried solid for laboratory work. Catalogue listings use the spellings epitalon, epithalone, and simply AEDG, and the three refer to the same sequence.
The compound is generally presented as a synthetic fragment of epithalamin, a pineal gland extract investigated in the former Soviet Union from the 1970s onward. Vladimir Khavinson and colleagues in Saint Petersburg developed short peptides modelled on such extracts, and epitalon became the most widely cited of those sequences. Most primary reports appeared in Russian-language journals or in proceedings with limited international circulation. Independent replication in laboratories outside that network remains sparse, and much repeated secondary material traces back to a small number of originating groups.
Laboratory work has examined effects on telomerase activity in cultured cells, on melatonin rhythms in animals, and on markers of oxidative stress. Some experiments report measurable changes while others show none, and the reported findings rest largely on small studies. The absence of large independent trials means the generality of these results is unresolved rather than settled. Review articles occasionally apply the label geroprotector, a term that reflects a research hypothesis about ageing rather than an established clinical finding.
Epitalon is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, abbreviated AEDG. Its molecular formula is C14H22N4O9 and its calculated monoisotopic mass is approximately 390.35 daltons. The compound does not occur naturally as a free peptide; it is produced by solid-phase peptide synthesis. Because it contains two acidic residues and no basic residues, the neutral form carries a net negative charge at physiological pH. This charge profile influences how the peptide behaves in solution and during chromatographic analysis.
Laboratory-grade epitalon is typically supplied as a lyophilized powder. Purity is commonly assessed with reverse-phase high-performance liquid chromatography, often paired with mass spectrometry to confirm molecular identity. Amino acid analysis and peptide mapping can provide additional confirmation of sequence. Certificates of analysis for research materials frequently report purity above 95 percent, although the methods behind such figures vary between suppliers. The absence of a pharmacopeial monograph means that no single standardized assay defines the compound, so reported results depend on the analytical protocol chosen.
Epitalon is a synthetic tetrapeptide whose sequence is alanine-glutamate-aspartate-glycine, written in single-letter code as AEDG. The four residues are joined by three peptide bonds, giving a linear backbone with no branching and no disulfide bridges. Its calculated molecular mass for the free form is approximately 390.3 daltons, a figure that rises when the compound is supplied as an acetate or trifluoroacetate salt. Because the chain is short, the molecule is defined entirely by its residue order rather than by any folded three-dimensional structure.
The compound is described in the literature as a derivative of epithalamin, a preparation obtained from bovine pineal tissue. Work on this peptide family was carried out mainly by a research group in Saint Petersburg beginning in the 1980s, and the substance was later registered for clinical use in Russia under the name Epitalon. Outside that region it is generally treated as a research chemical rather than an approved medicine. Statements about its biological activity rest on a relatively small number of studies, and independent replication remains limited.
The parent extract epithalamin was characterised as a low-molecular-weight fraction of pineal tissue rather than a single defined chemical entity. Researchers fractionated it and tested successive fragments for activity, a screening approach typical of peptide discovery work in that era. Epitalon emerged from that process as one of the shorter sequences of interest. Because the original extract was never fully resolved into individual components, claims about which constituent drives a given effect rest on inference. This distinction matters when reading older reports that attribute extract observations to the tetrapeptide itself.
Epitalon is a synthetic tetrapeptide with the residue sequence alanine-glutamate-aspartate-glycine, commonly abbreviated AEDG. Its monoisotopic mass is approximately 390.35 daltons, and it is usually supplied as a lyophilised trifluoroacetate or acetate salt. The compound was derived from a pineal gland extract called epithalamin, a heterogeneous preparation investigated in the former Soviet Union. Researchers associated with the Saint Petersburg Institute of Bioregulation and Gerontology described the tetrapeptide as a constituent fragment of that extract. Commercial material is offered as a laboratory reagent rather than as a finished pharmaceutical product.
== Structure == The carbohydrate moieties of AGPs are rich in arabinose and galactan, but other sugars may also be found such as L-rhamnopyranose (L-Rhap), D-mannopyranose (Manp), D-xylopyranose (Xylp), L-fucose (Fuc), D-glucopyranose (Glcp), D-glucuronic acid (GlcA) and its 4-O-methyl derivative, and D-galacturonic acid (GalA) and its 4-O-methyl derivative. The AG found in AGPs is of type II (type II AGs) – that is, a galactan backbone of (1–3)-linked β-D-galactopyranose (Galp) residues, with branches (between one and three residues long) of (1,6)-linked β-D-Galp. In most cases, the Gal residues terminate with α-L-arabinofuranose (Araf) residues. Some AGPs are rich in uronic acids (GlcA), resulting in a charged polysaccharide moiety, and others have short oligosaccharides of Araf. Specific sets of hydroxyproline O-β-galactosyltransferases, β-1,3-galactosyltransferases, β-1,6-galactosyltransferases, α-arabinosyltransferases, β-glucuronosyltransferases, α-rhamnosyltransferases, and α- fucosyltransferases are responsible for the synthesis of these complex structures. One of the features of type II AGs, particularly the (1,3)-linked β-D-Galp residues, is their ability to bind to the Yariv phenylglycosides. Yariv phenylglycosides are widely used as cytochemical reagents to perturb the molecular functions of AGPs as well as for the detection, quantification, purification, and staining of AGPs. Recently, it was reported that interaction with Yariv was not detected for β-1,6-galacto-oligosaccharides of any length.
The tags contain four regions, namely a mass reporter region (M), a cleavable linker region (F), a mass normalization region (N) and a protein reactive group (R). The chemical structures of all the tags are identical but each contains isotopes substituted at various positions, such that the mass reporter and mass normalization regions have different molecular masses in each tag. The combined M-F-N-R regions of the tags have the same total molecular weights and structure so that during chromatographic or electrophoretic separation and in single MS mode, molecules labelled with different tags are indistinguishable. Upon fragmentation in MS/MS mode, sequence information is obtained from fragmentation of the peptide back bone and quantification data are simultaneously obtained from fragmentation of the tags, giving rise to mass reporter ions.
=== 12 April === Russian-installed officials in Zaporizhzhia Oblast claimed that ten people were killed by Ukrainian shelling in Tokmak. One person was killed by Russian shelling in Kharkiv Oblast. Two people were killed in separate Russian attacks in Donetsk Oblast. Russia reported shooting down four drones over an oil refinery in Novoshakhtinsk. One drone fell in the grounds of the oil refinery. Another drone was reportedly shot down over Belgorod Oblast. A former SBU agent who defected to Russia shortly before the 2022 invasion was injured in a car bombing in Moscow. Russia and Ukraine conducted an exchange of war dead, with 99 Ukrainians being exchanged for 23 Russians. The HUR said that Russia had transferred 2,000 personnel from its Pacific Fleet and 400 personnel from the Russian Air Force's 11th Air and Air Defence Forces Army, in addition to halting the deployment of soldiers to Syria on rotation. It claimed that the transfers will either form new units or fill losses in existing units. Norway announced that it would transfer 22 F-16s to Ukraine as well as spare parts, simulators and other equipment to operate them.
Sources: en.wikipedia.org
Early specimens represent birds that were pets or came from menageries. The oldest surviving bird specimens include an African grey parrot once owned by Frances Teresa Stuart (1647–1702) that was buried with its owner in London’s Westminster Abbey. Several mummified ibis and falcons have been recorded from Egyptian tombs dating from 600 to 300 BC. Bird specimens obtained from the 18th century for natural history collections were most often obtained using firearms. Shotguns with "dust" shot were preferred to reduce damage to the specimens. Today, specimens come from a variety of sources. Many (perhaps most) are salvaged from birds killed by window and communications tower strikes, domestic cats, by-catch from fisheries, die-offs from disease, vehicle strikes, and other accidental sources of mortality. However, the world's bird collections have been argued to be inadequate in documenting avian diversity, from taxonomic, geographic, and temporal perspectives, with some parts of tropical regions considered under-represented in particular museums. Underrepresented taxa continue to be actively collected by ornithologists, generally using either firearms or mist-nets. Permitting agencies oversee these activities in most countries.
== Availability == PRRT is not yet widely available, with various radiopharmaceuticals at different stages of clinical trials. The cost of small volume production of the relevant radionuclides is high. The cost of Lutathera, a commercial 177Lu-DOTATATE product, has been quoted by the manufacturer as £71,500 (€80,000 or $94,000 in July 2018) for 4 administrations of 7.4 GBq.
=== Mark Healy === Mark Healy is played by Glenn Quinn. Mark begins dating Becky when she is about sixteen years old, much to the Conners' consternation. He comes from a dysfunctional family. Mark is mechanically inclined, but unlike his younger brother, David, he is not very intelligent, is a poor student, and has few goals in life. Mark elopes with Becky when she is only seventeen. She drops out of high school to be with him when he leaves town after losing his job at Dan's failed bike shop. They move to Minneapolis for his new mechanic's job. Despite Mark's tough-guy image and rebel persona, he is only occasionally seen engaging in minor criminal activity, such as underage drinking and using a fake I.D. Roseanne and Dan initially detest Mark, considering him a disrespectful and condescending punk. They grudgingly tolerate him as Becky's boyfriend and later son-in-law. Mark's choice to ride a British Triumph motorcycle rather than an American Harley-Davidson did cause particular tension with Dan. However, Dan comes to respect Mark's work ethic and hired him as a mechanic at his bike shop and later at the Lanford city garage. Mark's personality changes over the course of the series — starting off as a rebellious delinquent but ultimately softening and proving himself to be a caring and responsible (though comedically dull-witted) husband to Becky. He is also a loyal brother, though Mark enjoys tormenting the more intelligent David and mocks his artistic and sensitive personality.
Sources: en.wikipedia.org
Ansuvimab was developed by the Vaccine Research Center with support of the United States National Institutes of Health and the Defense Advanced Projects Agency. The heavy and light chain sequences of ansuvimab mAb were cloned into CHO cell lines to enable large-scale production of antibody product for use in humans. In early 2018, a Phase 1 clinical trial of ansuvimab's safety, tolerability and pharmacokinetics was conducted by Dr. Martin Gaudinski within the Vaccine Research Center Clinical Trials Program that is led by Dr. Julie E. Ledgerwood. The study was performed in the United States at the NIH Clinical Center and tested single dose infusions of ansuvimab infused over 30 minutes. The study showed that ansuvimab was safe, had minimal side effects and had a half-life of 24 days. A license for ansuvimab was obtained by Ridgeback Biotherapeutics in 2018, from the National Institutes of Health-National Institute of Allergy and Infectious Diseases. Ansuvimab was given orphan drug status in May 2019 and March 2020.
The NK-92 cell line is an immortalised cell line that has the characteristics of a type of immune cell found in human blood called 'natural killer' (NK) cells. Blood NK cells and NK-92 cells recognize and attack cancer cells as well as cells that have been infected with a virus, bacteria, or fungus. NK-92 cells were first isolated in 1992 in the laboratory of Hans Klingemann at the British Columbia Cancer Agency in Vancouver, Canada, from a patient who had a rare NK cell non-Hodgkin-lymphoma. These cells were subsequently developed into a continuously growing cell line. NK-92 cells are distinguished by their suitability for expansion to large numbers, ability to consistently kill cancer cells and testing in clinical trials. When NK-92 cells recognize a cancerous or infected cell, they secrete perforin that opens holes into the diseased cells and releases granzymes that kill the target cells. NK-92 cells are also capable of producing cytokines such as tumor necrosis factor alpha (TNF-a) and interferon gamma (IFN-y), which stimulates proliferation and activation of other immune cells.
The image above shows the interpretation of an antibody panel used in serology to detect antibodies towards the most relevant blood group antigens. Each row represents "reference" or "control" red blood cells of donors which have known antigen compositions and are ABO group O. The + symbol means that the antigen is present on the reference red blood cells, and 0 means it is absent; nt means "not tested". The "result" column to the right displays reactivity when mixing reference red blood cells with plasma from the patient in 3 different phases: room temperature, 37 °C and AHG (with anti-human globulin, by the indirect antiglobulin test).
Sources: en.wikipedia.org
It is a synthetic tetrapeptide with the sequence alanine-glutamate-aspartate-glycine, often abbreviated AEDG. The molecule is linear and contains no modified residues, so it is fully described by its sequence.
The compound came out of work on epithalamin, a peptide preparation derived from pineal tissue, conducted largely in Russian laboratories. Later studies in other countries examined it mainly in cell cultures and animal models.
The tetrapeptide sequence is a synthetic construct rather than a described circulating peptide. It was derived by analogy to peptide fractions obtained from tissue extracts, not isolated from blood or tissue as such.
It is a synthetic tetrapeptide. Its sequence was derived from research on peptide fractions of bovine pineal extract, and the intact AEDG sequence has not been demonstrated as an abundant free peptide in human tissue.